Selective system



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F. A. HUBBARD SELECTIVE SYSTEM 3 Sheets-Sheet 3 Filed Oct. 3l, 1940 WOM.

A 7' TOR/VEV Patented Nov. i' 3, 1942 SELECTIVE SYSTEM,

Francis A. Hubbard, Maplewood,

N. J., assigner Bell Telephone Laboratories, Incorporated,

New York, N. Y., a corporation of New York Application October 31, 1940,Serial No. 363,726 1 Claim. (Cl. 177 -353) This invention relates to thecontrol and operation of switches and particularly switches -used intelephone or other communication systems.

The objects of the invention are to simplify the circuits and devicesrequired for the selective operation of automatic switches; tofacilitate the use of common equipment for performing these selectiveoperations; to enable the selective operation of a large number ofswitching devices over a relatively few signaling or controllingconductors; and in other respects to realize improvements in switchingsystems.

Switches have been proposed heretofore comprising coordinate rows vofrelays or magnets together with selective means for selecting andoperating any desired one of the relays to close the corresponding setof circuit-making contacts. Also it has been proposed to usespace-discharge tubes at the coordinate cross-points for the purpose ofeffecting the operation of the corresponding relays. Other systems havebeen devised in which the circuits are established -by the coordinatelyarranged tubes without the aid of relays or magnets.

According to a feature of the present invention advantages are realizedover these prior arrangements by means of a switching system in whichany one of a large group of switching relays or magnets may be selectedand operated under the control of a much smaller group of controllingdevices, such as space-discharge tubes. More specically this improvedswitching system may comprise a group of switching magnets electricallyarranged in vertical and horizontal coordinate rows together with agroup of discharge tubes having as many tubes as there are vertical rowsof magnets and a second group of discharge tubes having as many tubestherein as there are horizontal rows of magnets. These tubes areconnected to the magnets in such a way that the magnet at theintersection of any vertical and horizontal row may be selected andoperated by causing the simultaneous discharge of the tube 4be appliedto any group of in the rst group corresponding to the vertical row andthe tube in the second group corresponding to the horizontal row.

Another .feature is a system of this kind in which each magnet isincluded in series with the main discharge gap of a tube in one groupand in series with the main discharge gap of a tube in the .other group,and in which the tubes are provided with separate control electrodeswhereby any pair of tubes, one in each group, may be dischargedsimultaneously.

Another feature is a switching system of this kind in which the tubes ineach of the two groups are selectively operated over a single conductorby time-separated impulses, each tube in the group being arranged tooperate only when it receives impulses of a particular phase.

Another feature of the invention is a switching system in which theoperating magnets of a plurality of cross-bar switches on a switch framemay be operated over a pair of signal conductors extending from a commoncontrolling mechanism to the switches, the controlling mechanism beingarranged to send signal currents to eiect the operation of any desiredswitch magnet.

These and other features of the invention will be described in detail inthe following specication and will also be set forth in the appendedclaim.

In the drawings accompanying the specification:

Fig. 1 illustrates a frame of switches to which the present invention isapplicable; and

Figs. 2 and 3 illustrate a group of magnets or relays together with theassociated equipment for selecting and operating them.

The invention is applicable broadly to the selection and operation ofmagnets, relays and similar devices, such as discharge tubes, whenarranged electrically in coordinate groups. In particular it isapplicable to the selection and operation of any oneof the operatingmagnets of a plurality of cross-bar switches. Also the invention may beapplied to a single switch of the coordinate type in which thecross-point contacts are made `by individual relays, magnets ordischarge tubes. .Furthermore, the invention may magnets or relays,whatever their purpose, where it is possible to arrange themelectrically in coordinate rows for selection.

For the purpose of illustration herein it is assumed that the inventionis applied to a crossbar switching system in which it is desired toselectively operate the hold magnets of a plurality of 'cross-bar linekswitches.r Referring to Fig. 1, a frame of cross-bar lineswitches isillustrated diagrammatically comprising ten horizontal and ten verticalgroups of switches. Three horizontal groups are illustrated,the`No.`0,yNo. l and No. 9 horizontal groups. Similarly three of the tenvertical groupsl are illustrated, the remaining groups being omitted forthe sake of simplicity. For example, horizontal g'roup No. 0 containsten cross-bar switches including switches |00, |0| and |02. Similarlyhorizontal group No. 1 contains ten switches including switches |03,

|04 and |05; and the same is true of the remaining horizontal groups ofswitches, the ninth group including the switches |06, |01 and |08. Thevertical group No. contains ten switches including the switches |00, |03and |06, and the same is true of the remaining vertical groups. Each ofthese cross-bar switches contains select magnets and hold magnets foroperating the cross-bars; usually there are ten select magnets and tenhold magnets. For instance, the switch |00 has ten hold magnets |09,||0, ||2 I I3 and ||4. The switch |03 is provided with ten hold magnets||5, H6, ||1 ||8 and ||9. Also the No. 9 switch |061 in the verticalgroup No. 0 has the ten hold magnets |20, -|2|, |22 |23 and |24.Similarly, the remaining switches on the frame are provided with thesehold magnets.

Although the invention is not particularly concerned with any specifictype of cross-bar switch for use in the switching arrangementillustrated in Fig. 1, the switch disclosed in the patent to Reynolds,No. 2,021,329 of November 19, 1935, is suitable for this purpose.

The switches illustrated in Fig. 1 of the drawings serve to extendcalling subscribers lines to idle trunk circuits, and the selectiveoperation of these switches is determined by controlling circuits which-are usually provided in common to the line switch frame. For a betterunderstanding of a line switch system of this kind ref erence is made tothe patent to Carpenter, No. 2,235,803, of March 18, 1941.

The controllingv circuits whereby these line switch hold magnets areselectively operated in accordance with the present invention areillustrated in detail in Figs. 2 `and 3. These circuits serve a group ofone hundred hold magnets, which are arranged electrically in tenhorizontal and ten vertical coordinate rows. All ten of the horizontalrows of magnets are shown in the drawings, but only ve of the verticalrows are shown to avoid unnecessary duplication. Although any arbitrarygrouping of the hold magnets may .be employedpit may be assumed that thehundred hold magnets shown in Fig. 2 are the hold magnets of the tenswitches in the No. 0 vertical group of Fig. 1. For example, the No. 0horizontal row of magnets at the bottom of Fig. 2 are the ten holdmagnets of switch |00, including magnets |09, ||0, ||3 and ||4; the No.1 horizontal row of Fig. 2 are the ten hold magnets of switch |03,including magnets H5, IIB, ||1, ||8 and ||9; and the magnets in the No.9 horizontal row are the magnets of switch |06, including magnets |20,|2|, |23 and |24.

The operating circuits for the magnets shown in Fig. 2 are controlled bytwo groups of space discharge tubes 200 and 300, each group containingten tubes. The tubes Aof the group 200 are individual respectively totheten horizontal rows of magnets; and the several tubes of the group 300are individual respectively to the ten vertical rows of magnets. Theanode element of each tube in the horizontal group' 200 is connected inmultiple to the operating windings of all magnets in the Aassociatedhorizontal row; and the cathode element of each tube in the verticalgroup 300 is connected in multiple to the operating windings of allmagnets in the associated vertical row. For example, anode 20| of tube202 is connected to conductor 203 which is wired in multiple to theupper terminals of the lefthand or operating windings of all magnets|09, ||0, ||3, ||4, in the horizontal row; and the cathode element 30|Vof tube 302 is connected to conductor 303 which is wired in multiple tothe lower terminals of theoperating windings of all magnets in theassociated vertical row, including magnets |09, ||5 and |20. Thecathodes of all tubes in the group 200 are connected in multiple loverconductor 204 to the negative pole of battery 205; and the anodeelements of all tubes in the group 300 are connected over conductor 304to the positive pole of battery 305.

The tubes of the groups 200 and 300 are discharged selectively byapplying to their control gaps brief potential impulses of differentphases, that is, impulses occurring at diiere'nt points in time, theselection of any desired tube being made by applying to its control gapimpulses of the appropriate phase. These impulses are preferably ofopposite polarities, impulses of one polarity being applied vto one ofthe control electrodes of a tube and impulses of the opposite polaritybeing applied to the other control electrode. Since these positive andnegative impulses are applied simultaneously to the same tube,ionization results, and the tube discharges. Hence it is possible toobtain selection among the ten tubes of the group by applying to one ofthe control electrodes of each tube impulses of a particular one of theten different phases and of a given polarity and by applying to theother control electrode of all tubes impulses of a desired phase and ofthe opposite polarity. Since impulses of only one phase are applied toonly one side of all of the control gaps, only one tube in the groupoperates.

The impulses of the ten different phase positions which are constantlyapplied to one side of the control gaps of the tubes in the group 200,are supplied by the impulse generator 206, which derives its energy forproducing the impulses from a source of alternating current 225. Theimpulse output circuits of this generator are connected through suitabletransformers 201, 208, 209, etc., to the control electrodes 2|0, 2H,2|2, etc., of the respective tubes in the group 200. Thus impulses ofphase position No. 0 are constantly applied through the transformer 201to the control electrode 2|0 of the tube 202, impulses of phase positionNo. 1 are constantly applied to the control electrode 2|| of tube 2|3,impulses of phase position No. 2 are constantly applied to the controlelectrode 2|2 of tube 2|4, and likewise for the remaining tubes of thegroup. 'I'he impulses of the ten diierent phases, which are constantlyapplied to one side of the control gaps of the tubes in the group 300,are supplied by the impulse generator 306, which derives its energy forproducing these impulses from a source of alternating current 340. Theseimpulses are also transmitted through transformers in the several supplycircuits. For example, impulses of phase position No. 0 are appliedthrough transformer 301 to the control electrode 309 of tube 302,impulses of phase position No. 1 are applied through the transformer 309to the control electrode 3|0 of tube 3||, and likewise impulses of theremaining phase positions are constantly applied through individualtransformers to the control electrodes of the corresponding tubes of thegroup 300.

The selection of the proper tube in the vertical group and the propertube in the horizontal group is determined by a common control mechanism3|2. The control mechanism 3|2 includes impulse generators 3|3 and 3|4,supplied by sources 34| and 342, these sources and sources 225 and 340all being of the same frequency and phase. Each of the generators 3|3and 3|4. therefore, produces impulses o! the same phases as thoseproduced by the generators 206 and 306. The polarities, however, areopposite. Inother words, if the generators 206 and 306 apply impulses ofpositive polarity to the tubes in the groups 200 and 300, respectively,the generators 3|3 and 3|4 are designed to apply impulses of negativepolarity to these tubes. II desired, of course, the generators 206, 306,3|3, and 3|4 may all be supplied from a single source of alternatingcurrent.l

'I'he impulse generators 206, 306, 3|3 and 3|4 for producing impulses ofdiii'erent phases may be of any suitable type, such as those disclosedin detail in therapplication oi' W. H. T. Holden, Serial No. 361,536,illed October 17, 1940; and the patents to Holden No. 2,252,766 ofAugust 19, 1941, and No. 2,285,815 of June 9, 1942.

The infomation identifying the cross-bar switch on the frame and theparticular hold magnet that should be operated is transmitted to thecontrol mechanism 3|2 in any suitable manner and is utilized to selectthe proper one of the phase output circuits of the generators 3| 3 and3|4. The phase output circuits 3|5 of the generator 3|3 appear in somesuitable selecting device such as the step-by-step switch 3|6. Likewisethe phase output circuits 3|'| of the generator 3|4 appear in thecontact points of the selector switch 3|8. The brushes 3|9 and 320 ofthese switches are connected through a connector relay 32| to thecontrol electrodes of the tubes in groups 200 and 300, respectively.

A better understanding of the manner in which the system operates may beobtained from a brief description of the operations involved in theselection of a particular one of the hold magnets. For this purposeassume that it is desired to operate the hold magnet of the switch |03.Since the magnet is in the No. 1 horizontal group and in the No. 5vertical group of the hundred magnets, shown in Fig. 2, the informationreceived by the control mechanism 3|2 causes the switch 3|6 to positionits brush 3|9 on the No. l phase circuit 322 and the switch 3|8 toposition its brush 320 on the No. 5 phase circuit 323.

At the proper time the connecting relay 32| is operated to connect thecontrol mechanism 3|2 to the group of one hundred magnets. An impulsetransmitting circuit is now completed from the generator 3|3 overconductor 322, brush 3|9, conductor 324, contact of relay 32|, conductor325'through resistance 2|5 to ground and also in multiple to the rightcontrol electrodes of all tubes in the group 200. Negative impulses ofphase No. l are therefore applied over conductor 325 to the rightelectrodes of all tubes 200. These impulses are in phase with thepositive impulses applied to the left electrode 2|| of tube 2|3 and areout of phase with the impulses applied to the left electrodes of allother tubes in the group. The simultaneous application of a negativeimpulse to electrode 2|6 and a positive impulse to electrode 2|| causesthe ionization of the control gap of the tube 2|3, whereas the remainingtubes in the group remain deionized. Since the ten different phaseimpulses produced by the generators 206 and 306 occur in one-half cycleof the sources of supply voltage, as disclosed in the Holden patentabove mentioned, No. 2,285,815, of June 9, 1942, any tube that isionized in the group 200 in response to an incoming phase impulse may belocked in an ionized condition for the remainderof said halt cycle ofthe supply voltage. Therefore, the tube 2|3, when initially ionized inresponse to the incoming impulse of phase No. 1, is locked-in an ionizedcondition over a circuit from battery 2H, resistance 2|0, resistance223, controlgap 2| |2|6 of tube 2|3, resistance 2|5 to ground. Althoughthe battery 2H alone is not sumcient to ionize the control gap of thetube. it is sumcient when supplemented by the voltage produced by thetransformer 224 during the remainder oi.' the half cycle to maintain atube, once iired, in an ionized condition. Therefore, the tube 2|3, orany other one of the ten tubes that is ionized in any one of the tencorresponding phase positions occurring in the half cycle of the source226, is

maintained in an ionized condition, following the cessationgof theionizing impulse, through the remainderof the half cycle by means ofthebattery 2I1 and the voltage produced across the resistance 2|8 by thetransformer 224.

Similarly, an impulse circuit is established from the generator 3|4 overconductor 323, brush 320, conductor 326, contacts of relay 32|,conductor 321, through resistance'328 to groundand in multiple to theleft control elements of all tubes inthe group 300. 'I'hus impulses ofphase No. 5 vare transmitted over the conductor 321 to the tubes 300.Only the tube 329 responds to these impulses since both positive andnegative impulses of the same phase are being applied to its controlelectrodes. When the tube 329 ionizes in the fth phase position of thehalf cycle of the source 340, which source may be of the same phase andfrequency as the source 225, a locking ionizing circuit is closed frombattery 330, resistance 33|, resistance 339, control gap 332-333 of tube329, resistance 328 to ground. The voltage of battery 330 whensupplemented by the voltage produced across the resistance 33| duringthe remaining half cycle of the source 340 is suicien-t to maintain thecontrol gap of the tube 329 ionized. Since both tubes 2|3 and 329 arenow in an ionized condition, a main discharge circuit is closed throughthese tubes and through the operating winding of the desired magnet Thiscircuit may be traced from the positive pole of battery 305, conductor331, contacts of relay 32|, conductor 304, anode 334 and cathode 335 oftube 329, conductor 336, left winding of magnet conductor 2 I9, anode220 and cathode 22| of tube 2 |3, conductor 204 to the negative pole ofbattery 205. The current owing in this series circuit operates themagnet which closes a holding circuit in any well-known manner throughits right winding and the contacts of the switch controlled by themagnet. At the end of the half cycle of the supply sources 225 and 340and at the end of each successive corresponding alternation the voltageacross the control gaps of the tubes 2|3 and 329 drops to the voltage ofthe batteries 2|`| and 330, respectively, which is insuiilcient tomaintain these control gaps in an ionized condition.

As soon as the control circuit 3|2 has completed its functions, theconnector relay 32| is released to disconnect the control circuit fromthe switch frame. The release of relay 32| opens the circuit of battery305, or if desired this circuit may be opened at any other point, andthe tubes 2 |3 and 329 deionize, thus opening the circuit for thefurther ilow of current through the operating winding of the magnet I Asabove mentioned,

however, the magnet Ill has already locked over its right windinx.

In the manner already described it is possible to select and operate themagnet at tthe intersection of any one of the horizontal and verticalrows by applying an impulseof4 the proper phase to the group oi tubes200 and an impulse ofthe proper phaseto the group of tubes 300, botl'iof these impulses occurring within the same half cycle of the sources225 and 340.' v

As above noted, the selecting arrangement shown in Figs. 2 and 3 servesthe magnets of the vertical group No. of switches illustrated in Fig. 1.It' will valso be understood that similar switching arrangements may beprovided for each of the remaining vertical groups of switches on theframe.

Although the operating .windings ot the magnetsl shown in. Fig. 2are'connected to common circuits on both sides, no interference will beencountered provided the magnets are designed and a particular tube inthe second series, means for generating repeatedly impulses of asuccession of diierent phases, circuit means for applying the impulsesof the successive phases respectively to one of the control electrodesof the successive tubes of each series. circuit means for applyingselectively impulses of any one ot said phases to the other controlelectrodeof eachof the tubes in the iirst series to cause the selectiveionization of the particular tube therein having impulses of the samephase applied to both of its control electrodes, circuit means forapplying selectively impulses of any one of said Phases to the othercontrol electrode of eachof the tubes in the second series to cause theselective ionization of the particular tube therein having impulses ofthe same phase applied to both of its control electrodes, means formaintaining any one ot the tubes in `eitl'ier one of said series in itsionized condition following the application of the ionizing phaseimpulses to the control electrodes thereof and until one of said tubesin the other series is ionized by the application of the correspondingphase impulses to the control electrodes thereof, and a main dischargecircuit including the main electrodes of each of the pair of ionizedtubes in said sexies and also including the operating winding ott theelectromagnet represented by said pair of tubes.

FRANCIS A. HUBBARD.

